Formation of tube ends



May 9, 1950 H. N. WEBSTER 2,506,657

FORMATION OF TUBE ENDS Filed June 4, 1947 2 Sheets-Sheet 1 WITNESSES I NV EN TOR:

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y 1950 H. N. WEBSTER 2,506,657

FORMATION OF TUBE ENDS Filed June 4, 1947 2 Sheets-Sheet 2 Q as m 1 QL56 I M I WITNESSES 1 N V EN TOR:

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Patented May 9, 1950 2.506.051 A FORMATION OF TUBE ENDS Henry N.Webster, Sebring, Fla., assignorlo Webster Corporation, Sebring, Fla., acorporation of Florida Application June 4, 1947, Serial No. 752,424

1 Claim. (Cl. 29-156) This invention relates to an improvement in theexpansion, working and forming of thin walled tubes and moreparticularlyto the formml of an expanded end portion thereof.

It is old to expand metallic tube ends by means of a plunger forcedwithin the end. It is also old to couple with the use of such plunger anoutside die to coact with the inner operation of the plunger, formingthe tube end between the die and plunger. I have found in practice thatneither of these methods is effective in working with extruded aluminumtubing having a comparatively thin wall because both of these methodsresult in numerous failures by splittin or fracture. Of course, the sameproblem is present with any thin walled pipe manufactured by theextrusion proces in which the metal grain tends to run in an axialdirection. There are disadvantages in attempting to obtain strength bythickening the wall of a tube which must be portable and therefore lightas in the case ofv a portable section of a movable irrigation pipe line.A thicker tube wall means added weight, the expense of the additionalmetal and the added difllculty in forming thick walls of the pipe end toparticular shapes to form a joint. This problem became particularlyacute where it was necessary to first enlarge a thin walled aluminumpipe end and thereafter further work and. shape that enlarged portion ofthe pipe to form the female element of a pipe Joint.

The object of my invention, therefore, is to provide an effective meansfor expanding or working the. end of, a thin walled metallic tubemanuf'actlired by the extrusion process. Another obj ect of my inventionis the provision of means for expanding such tube ends without weakeninor reducing the wall thicknessthereof in the expanded portion. Anotherobject of my invention is the provision of a means for expanding suchtube end without subsequent splitting or fracturing. Another object ofmy invention is the provision of a. means for forming the ends of tubesof the type referred to above into the female elements of a pipe jointwithout weakening the area at the joint. Still further objects andadvantages will become apparent fromthe following detailed descriptionof a preferred form of my invention, reference being had to the'accompanying drawings.

Of these drawings, Fig. 1 is a conventional showin partially in .sectionof apparatus illustrating the performance of the first stage of themethod of my invention.

Fig. 2 is the same as Fig. 1 except that it illusof the tube 6.

2 trates a later stage of the performance of the method of my invention.

Fig. 3 is the same as Figs. 1 and 2 except that it shows a still laterstage of the performance of the method of m invention.

Fig. 4 shows a top plan view of apparatus providing a pair of rollerdies which may be employed in a combined rolling and spinning operationas required in the final stage of the practice of the method of myinvention.

Fig. 5 is a front elevation of-the apparatus of Fig. 4 with parts brokenaway and shown in section to better disclose important details of thestructure and operation thereof.

Fig. 6 is a partial front view of the apparatus of Fig. 5 showing theroller dies at the completion of the combined rolling and spinningoperation.

Fig. 7 is a partial end view of the apparatus looking from the righthand side of Fig. 6.

In describing the embodiment of this invention shown in the drawings, aspecific terminology will be adopted for the purpose of clarity, but itis to be understood that it is not intended thereby to limit theinvention to this detailed description of an illustrative embodimentthereof. Each term adopted is intended to include all equivalentsthereof which operate in a substantially similar manner to accomplish asubstantially similar resuit.

The practice of the method of my invention involves a plunger I mountedon a hydraulic power means comprehensively designatedas 2, a bracket 3supporting said power means 2 and mounted on a base or frame member 4,9. retaining ring 5 manually positioned at the end of the tube 6, adraw-down die 1 receiving an end of the tube 6 supported by a bracket 8and the base or frame member 4 and a pair of roller dies l0 and IIsuitably supported and mounted as will be explained in detail later.

The plunger I is formed with a guiding or piloting section IS with anoutside diameter equal to or very slightly less than the inside diameterThe piloting section l5 should snugly fit inside the tube 6 withoutsubstantial expansion thereof and thus function in aligning the plungerl and the tube 5. The section 15 merges with an inclined section l5which should be formed with a pronounced angle to the horizontal surfaceof section IS in order to provide a substantial thrust component totransmit an upsetting effect to the tube wall as the plunger l is forcedinto the tube 6. I have found than an angle of 30 gives' excellentresults and provides the necessary thrust component in the direction ofthe axis of the tube 0. Of course this angle can be decreased providedthe angle is sufllcient to effect a substantial thrust component toobtain the upsetting effect on the tube wall. For example, if this angleis so reduced that the plunger I operates primarily in performing astretching and expanding function the benefits of my invention will notbe obtained. The tube end will tend strongly to fracture or splitbecause the force and effect of the die I is expended almost entirely ina radial direction. This is a mere stretching which clearly reduces thewall thickness of the tube 6. The same unsatisfactory resuits areobtained when it is attempted to expand the tube end by hydraulicpressure confined within the tube end and for the same reason. Accordingto my invention the provision of a sharp enough angle to provide a forcecomponent exerting an axial thrust within the tube 3 results iri asubstantial upsetting effect on the tube wall which increases ratherthan decreases the wall thickness. In fact I have observed in thepractice of my invention an increase of wall thickness of between 2 tothousandths of an inch in thickness. On the other hand, if the angle ofsection II of the plunger I is too great, failures will develop becauseof buckling or gathering. It will thus be apparent to those skilled inthe art that my invention involves the selection of an angle in sectionI5 which will provide a flow plane for the metal and at the same timeexert a substantial axial thrust force on the tube 6. Section I6 mergesinto section I1 which receives the metal as it flows up and over sectionI6. Section I! is the diameter of the inside of the expanded portion andmay be as much as 20% greater than the original inside diameter of thetube.

It is very important in view of numerous experiments to promote thelongitudinal and easy flow of the metal in the wall of the tube 6 assection is of the plunger I enters the tube 6. It should be rememberedin this connection that the grain structure of a tube formed by theextrusion process is inclined to run axially of the tube and myinvention thus takes advantage of the existing grain condition. It hasbeen found that the benefits of my invention are not obtained when anouter die of the usual type is provided. Apparently an outerconfiningdie interferes with the easy flow of metal up the flow plane of sectionI6 and onto section II of the plunger I. On the other hand, fractures,splitting and undesirable flaring develop when the plunger I is usedwithout outside support at the terminal edge of the tube 6. Therefore,according to my invention, I provide an axially short circular retainingring 5, recessed at 20 to receive the terminal edge of the tube 6 at itsexpanded diameter as in Fig. 3. This retaining ring 5 holds the end ofthe tube 6 without unduly restraining the free flow of the metal up andover the flow plane of section I6 and on to the section I! of theplunger I.

In operation, the retaining ring 5 is manually positioned around theterminal edge of the tube end as shown in Fig. 1 until the flaring edge,of

the. tube 6, developing from the action of the plunger I, is firmlyseated in the recess 20 of the retaining ring 5 as in Fig. 2. Fig. 3shows the retaining ring 5 at the conclusion of the expanding operation.When the plunger I is withdrawn, the ring 5 may easfly be removed byhand, being loosened,.if necessary, by a few taps from a hammer orsimilar instrument. It will be obvious that the length of the expandedportion of .details are well within the experience of the skilledartisan and have no direct bearing on the description of the method ofmy invention. The draw down die I is also of a conventional form wellknown to the art and need not therefore be described in further detailhere except to point out the two steps in its functioning.

- This is effected by two spaced elements 22 and 23 which together makeup the draw down die I. Element 22 reduces the diameter of the tube 6and element 23 rounds in the end of the tube 8 as will be seen fromFigs. 2 and 3. Clearly, the

length of the reduced section of the tube 3 depends upon the spacing ofthe elements 22 and 23 by the spacing rods 24. The pressure exerted bythe power means 2 in forcing the plunger I into the tube 6 is alsotransmitted through the length of the tube to effect the functioning ofthe draw down die I contemporaneously with the formation of the expandedend of the tube 6.

Having now described the expanding stage of the method of my invention,I will next turn to the final forming stage which involves the use of apair of roller dies consistingof inside roller I II and outside roller II having cooperating ridges and grooves formed thereon. Inside roller III is integrally mounted on a power driven shaft 25, the source of powerbeing any conventional type and therefore omitted in the drawing as notpertinent to my invention. The outside roller II is mounted for freerotation on axle member 26 supported by a U-shaped member or yoke 21with capacity for axial movement. It will be noted from Fig. 5 that theaxle member 26 is considerably longer than the width of the roller IIand the purpose of this is to allow sufficient free axial movement ofthe roller II to perform the spinning function as will be describedlater.

Tne yoke 21 is suspended by means of pivot connection 30 formed in theelement 3| integrally mounted on a lever or operating arm 32 by means ofnut 33 and lock washer 34 as shown in Fig. 5. It will be observed that asuitable vertical hole is formed in the arm 32 to receive the shankportion of element 3| therethrough. The arm 32 having a handle 39 ispivotally mounted on bracket 35 which is supported on the base or frame36 in a conventional manner.

Itwill be noted in Figs. 4 and 5 that the tube 6 is positioned at anangle in both the vertical and horizontal plane. This angularpositioning is done manually by an operator who holds the free end ofthe tube 6 during the operation. The purpose of this angularity is twofold: first, to positively hold the expanded end of the tube 6 onto thedriven inside roller Ill; and second, to cause the floating outsideroller I I to move to its proper operative position for starting theoperation of combined rolling and spinning, which is at the extremeright on axle member 26 as shown in Fig. 5. This position is promoted byan oil tracking effect between the tube Ii and the outside roller I Iresulting from the angularity referred to above. The pivotal connection30 permits the outside roller to contact the tube 8 at the two highpoints of its two ridges regardless of the angularity of tube 6. Theinside length of axle member 20 which determines the limits of the axialmovement of the outside roller ll within the yoke 21 should be such thatthe outside roller II in its initial operative contact with tube 6maintains its proper relation with the inside roller l0. The

points 40 on the tops of the ridges formed on the surface of outsideroller l I must be definitely and at all times to the left of the points41 on the tops of the similar ridges formed on the outside surface ofthe inside roller l0. -See Fig. 5. Because of this relationship betweenthe rollers II and l I, downward pressure exerted on the outside rollerll will cause the roller II to gradually move axially to the left asgrooves are rolled into the tube 8. The pressure exerted on the roller lI is controlled by an operator who exerts downward pressure on thehandle 39. This develops a spinning operation through the urging of themetal to the left as well as downwardly. In this way there is an axialmolding of the metal in the direction of the grain formation of the tube6. The grain condition in the tube 8 naturally lends itself to a flow ofmetal longitudinally of the tube 8 and thus the forming operation workswith the natural condition of this grain condition of the metal. At theconclusion of the combined spinning and rolling operation, the rollersI0 and l I appear as in Fig. 6.

While this invention has been described above in considerable detail andcertain modifications thereof suggested, it will be apparent to thoseskilled in the art that various other changes and modifications may bemade without departing of a thin walled metallic tube comprising first 6enlarging the area to be given a corrugated formation to a diameterequal to that of the tops of the external ridges to be formed in saidcorrugated area, said enlargement being effected by the forcing into theend of the tube of a plunger having an outwardly inclined portion, theangle of said inclination being sufficient to provide an up-settingefiect whereby the wall is not made thinner from the expansive eifect,the end portion of said tube being peripherally supported externallyduring the operation of said plunger by an axially short retaining ringwhich exposes without external support a substantial part of the tubeportion being enlarged, and thereafter rolling transverse corrugationsin said enlarged area of said tube, to the depth of the originaldiameter of the tube; and, by means of the rolling, simultaneouslymolding the metal inwardly and longitudinally toward the enlarged end ofthe tube.

HENRY N. WEBSTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,206,395 Widell Nov. 28, 19161,647,447 Hartnett NOV. 1, 1937 2,027,018 Brinkman Jan. '1, 19362,072,359 Dobrick Mar. 2, 1937 2,157,252 Visser May 9, 1939 2,241,091Hood May 6, 1941 2,243,932 Wery June 3, 1941 2,418,312 Michelman Apr. 1,1947 FOREIGN PATENTS Number Country Date 754,801 France Aug. 28, 1933

